The present invention is concerned with a combustion apparatus and a method for combusting a pressurized fuel, and with fuel mixtures for such combustion. More particularly, the present invention is concerned with combustion devices, e.g., space heaters, stoves and the like, of the type which have, or can be connected to, a self-contained fuel supply. With the prior art devices, such self-contained fuel supply may be propane gas cylinders or other containerized fuels. Such combustion devices are portable in the sense that their fuel supply is self-contained and are conveniently used in environments such as outdoors (by military units, by explorers, hikers or other campers), on board boats, and the like. Such combustion devices are sometimes referred to below as "self-contained" devices, combustion devices, stoves, etc.
Such self-contained combustion devices adapted to burn a variety of fuels are well known in the art. Alcohol is a particularly advantageous fuel for such self-contained devices because of its low explosion hazard and stability in transport and storage, the absence of suffocating fumes and generally low danger level in case of leakage of the fuel. Generally, liquid fuels have certain advantages over gaseous fuels for use with self-contained combustion devices because the explosion hazard associated with pressurized gas cylinders is avoided, liquid fuel is denser and therefore requires less storage volume per unit of heat energy available, and may be more readily available in the field.
Whether the fuel employed is alcohol, a hydrocarbon fuel such as kerosene, or any other suitable liquid fuel, a difficulty encountered in portable or lightweight stoves and the like is the difficulty of providing smooth, reliable combustion of the liquid fuel in a self-contained device which often must be lightweight or portable. The usual solution is to vaporize the liquid fuel and admix the vaporized fuel with air to provide a combustion mixture. Once the self-contained device is in operation, the liquid fuel can be readily vaporized by heating it from the combustion it is fueling, as by passing the fuel through a pre-heating tube or coil positioned to be heated by the combustion. However, vaporization of the fuel presents a problem in cold starts, because a preliminary heat source must be provided to vaporize the fuel. The art has expended considerable effort and ingenuity in attempting to overcome these and related problems.